Foxconn Technology Group, a key Apple supplier, is setting a bad example for industry by overworking its staff, according to a Chinese trade union.

The Taiwanese manufacturing giant has already received heaps of criticism, following a series of employee suicides back in 2010 that gave Foxconn and Apple a PR black eye. Although Foxconn has worked to improve conditions at its Chinese factories, the country’s official trade union still isn’t satisfied with the progress.

Foxconn is among the manufacturers that continually violate local laws on overtime hours, the All China Federation of Trade Unions said during a news conference Monday.

In Foxconn’s case, the working hours are so long that employees suffer from depression and other mental problems, which could lead to death by suicide or exhaustion, said Guo Jun, an official with the trade union.

The trade union wants to correct the problems, but some areas of China are still focused on economic development, at the expense of treating workers fairly.

“Many industries could learn from Foxconn, and decide to overwork their employees, in order to achieve greater profits,” Guo warned. If the offending companies aren’t punished, then the violations will only continue, he added.

It’s unclear if the trade union, controlled by China’s Communist Party, will do much to change the situation. Worker mistreatment and labor problems have persisted across the Chinese manufacturing industry for years, according to watchdog groups.

But on Wednesday, Foxconn responded to the trade union’s claims and defended its labor policies.

Manufacturers including Foxconn face the dilemma of appeasing employees who want to earn more, while also abiding by local regulations on overtime, it said in an email.

To address the problem, Foxconn has been raising wages, while strictly requiring that employees rest one day each week. In addition, its been using more automation in its manufacturing processes, to relieve workers of “dull and repetitive” duties.

Numerous experts and government officials have investigated Foxconn, and worked to resolve the problems, the company said, adding that “Guo Jun has never visited any Foxconn campus before.”

As part of its pledge to improve factory conditions, Foxconn has worked with the U.S.-based Fair Labor Association to correct any labor violations, although long overtime hours continues to be a problem. Chinese law demands that factories keep an employee’s work week under 49 hours, but audits have shown Foxconn struggling to meet that goal.

“We admit we are still far from perfect,” Foxconn said. “But we have always been making the effort.”

Foxconn employs over 1 million workers in mainland China, and in addition to Apple, it also builds products for Amazon.com, Microsoft, Sony and others.